1. Field of the Invention
The present invention relates to a water-based paint recycling method in which the paint mist generated during painting in a water-based paint application booth is recovered and reused, and more particularly relates to a water-based paint recycling method in which there is no need for the water-based paint application booth to be set up in proximity to the condensing separator.
2. Description of the Related Art
In an effort to conserve resources and energy, and to protect the environment, there have been attempts in recent years at recovering and reusing the paint mist that is generated when a water-based paint is sprayed onto the object being painted but does not adhere to this object.
For instance, Japanese Laid-Open Patent Application H5-214267 discloses a method for condensing a water-based paint in which the water-based paint is trapped in water to obtain a diluted paint, which is then filtered to remove the water and condense [the paint]. Japanese Laid-Open Patent Application H6-7718 discloses that recovered washing water with a concentration of 1 to 1.5 wt % is condensed by being sent through a two-stage ultrafiltration apparatus, and is then reused as a spray paint. Japanese Laid-open Patent Application H6-320103 discloses a method for reusing the liquid separated from recovered paint, in which a water-based paint is trapped in washing water to obtain a diluted paint, which is then separated into paint and water, allowing the paint to be recovered and the separated liquid to be reused as washing water. Japanese Laid-Open Patent Application H11-47653, meanwhile, discloses a shower coating system in which a water-based paint and washing liquid recovered from a shower coating booth are guided into an ultrafiltration circulation channel, the filtrate is taken off and collected in a filtrate tank, and the collected filtrate and any supplemental filtrate components added as necessary are used as a washing liquid, while condensate is further guided to the ultrafiltration circulation channel and the water-based paint concentration is brought to the application concentration, and the recovered water-based paint and any fresh water-based paint added as necessary are supplied to the shower coating process, with this process carried out continuously. All of the above publications disclose that the painting booth is connected by piping to the condensing separator where filtration, concentration, and separation are carried out, and that the same number of condensing separators are provided as painting booths.
However, whether the equipment is existing or new, providing a plurality of condensing separators in the vicinity of the painting booths is problematic in terms of both space and cost.
Also, connecting these components is substantially accomplished by laying out piping on site, and this piping is of considerable length and requires maintenance.
It is therefore an object of the present invention to provide a method for recycling a water-based paint, with which there is no need to install the condensing separator close to the water-based paint application booth, thereby affording greater freedom in layout.
The present invention is a water-based paint recycling method in which the paint mist that is generated when a water-based paint is applied in a water-based paint application booth in the bottom of which booth water is pooled is trapped by the booth water, after which the booth water containing the trapped paint mist is treated with a condensing separator to form condensate and filtrate which are reused, wherein the water-based paint application booth and the condensing separator are independent, not being connected by piping. Here, it is preferable if a plurality of water-based paint application booths are set up, and if the condensing separators are set up in a number smaller than the number of water-based paint application booths.
Here, in more specific terms, upon completion of the painting, the booth water pooled at the bottom of the water-based paint application booth is transferred to a transport tank, after which the booth water in the transport tank is transferred to the condensing separator. Further, the bottom of the water-based paint application booth is filled with fresh water after the booth water has been transferred from the bottom of the water-based paint application booth to the transport tank. It is also preferable if the inside of the transport tank is agitated.